TABLE I.

Determination of $D_0^{\prime }$ for photon beams using 10-cm normalization depth. For a nonisocentric system with 1 MU defined to deliver 1 cGy at 100 cm SSD and depth = d_m, the dose/MU is calculated at the suggested normalization conditions of d = 10 cm, 100 cm SAD, using depth of d_m and TMR data taken from Ref. 57. The suggested $D_0^{\prime }$ maintains the definition 1 MU under a new, 10-cm normalization condition.

Energy	d m	TMR		Dose/MU	Suggested $D_0^{\prime }$
(MV)	(cm)	(10, 10×10)	${\left(\frac{100+d_m}{100}\right)}^2$	(cGy/MU)	(cGy/MU)
4	1	0.738	1.020	0.753	0.750
5	1.25	0.759	1.025	0.778	0.780
6	1.5	0.786	1.030	0.810	0.810
8	2	0.820	1.040	0.853	0.850
10	2.3	0.839	1.047	0.878	0.880
12	2.6	0.858	1.053	0.903	0.900
15	2.9	0.877	1.059	0.929	0.930
18	3.2	0.896	1.065	0.954	0.950
21	3.5	0.914	1.071	0.979	0.980
25	3.8	0.933	1.077	1.005	1.000